An enzyme-based immunodetection assay to quantify SARS-CoV-2 infection

Antiviral Res. 2020 Sep;181:104882. doi: 10.1016/j.antiviral.2020.104882. Epub 2020 Jul 29.


SARS-CoV-2 is a novel pandemic coronavirus that caused a global health and economic crisis. The development of efficient drugs and vaccines against COVID-19 requires detailed knowledge about SARS-CoV-2 biology. Several techniques to detect SARS-CoV-2 infection have been established, mainly based on counting infected cells by staining plaques or foci, or by quantifying the viral genome by PCR. These methods are laborious, time-consuming and expensive and therefore not suitable for a high sample throughput or rapid diagnostics. We here report a novel enzyme-based immunodetection assay that directly quantifies the amount of de novo synthesized viral spike protein within fixed and permeabilized cells. This in-cell ELISA enables a rapid and quantitative detection of SARS-CoV-2 infection in microtiter format, regardless of the virus isolate or target cell culture. It follows the established method of performing ELISA assays and does not require expensive instrumentation. Utilization of the in-cell ELISA allows to e.g. determine TCID50 of virus stocks, antiviral efficiencies (IC50 values) of drugs or neutralizing activity of sera. Thus, the in-cell spike ELISA represents a promising alternative to study SARS-CoV-2 infection and inhibition and may facilitate future research.

Trial registration: NCT04433910.

Keywords: Antiviral testing; Drug screening; In-cell ELISA; Neutralization; SARS-CoV-2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Viral / immunology*
  • Betacoronavirus / immunology*
  • Betacoronavirus / isolation & purification
  • COVID-19
  • Chlorocebus aethiops
  • Coronavirus Infections / diagnosis
  • Coronavirus Infections / virology*
  • Enzyme-Linked Immunosorbent Assay / methods*
  • Humans
  • Pandemics
  • Pneumonia, Viral / diagnosis
  • Pneumonia, Viral / virology*
  • SARS-CoV-2
  • Severe Acute Respiratory Syndrome / diagnosis
  • Severe Acute Respiratory Syndrome / virology*
  • Spike Glycoprotein, Coronavirus / genetics
  • Spike Glycoprotein, Coronavirus / immunology*
  • Vero Cells
  • Viral Plaque Assay


  • Antibodies, Viral
  • Spike Glycoprotein, Coronavirus

Associated data

  • EudraCT/EudraCT 2020-001310